# year    value 
 1979 -2.611563 
 1980 -3.490502 
 1981 -2.856077 
 1982 -3.502111 
 1983 -4.538534 
 1984 -4.447981 
 1985 -3.782011 
 1986 -3.635148 
 1987 -2.417771 
 1988 -2.62495 
 1989 -3.406652 
 1990 -2.788674 
 1991 -3.048116 
 1992 -3.610759 
 1993 -2.99309 
 1994 -2.862574 
 1995 -3.534519 
 1996 -3.948817 
 1997 -3.346675 
 1998 -3.412066 
 1999 -1.533867 
 2000 -3.714254 
 2001 -2.571746 
 2002 -2.353345 
 2003 -2.505252 
 2004 -2.657855 
 2005 -3.186939 
 2006 -2.043511 
 2007 -2.478786 
 2008 -4.009061 
 2009 -1.531371 
 2010 -2.368164 
 2011 -3.41556 
 2012 -3.789731 
 2013 -2.91857 
 2014 -3.135965 
 2015 -2.301819 
 2016 -2.583443 
 2017 -1.134579 
 2018 -2.036619